This is an Extracts from Food Standards:

Most foods have a best before date. You can still eat foods for a while after the best before date as they should be safe but they may have lost some quality. Foods that have a best before date can legally be sold after that date provided the food is fit for human consumption.
The only food that can have a different date mark on it is bread, which can be labelled with a baked on or baked for date if its shelf life is less than seven days.
Foods that have a shelf life of two years or longer, e.g. some canned foods, do not need to be labelled with a best before date. This is because it is difficult to give the consumer an accurate guide as to how long these foods will keep, as they may retain their quality for many years and are likely to be consumed well before they spoil.